(Continued from https://lemmy.world/post/43278229 a few days ago...) So, I tried fully removable for the index, but that is impractical as far as the size, space, and complexity. I can't see a way of maintaining concentricity.
Next I tried making various hollow spaces where the main pawl slaps the index with every shift. I wondered if it would sound or feel any different, but no dice. Printed pawls (don't last long) sound very different. The index tooth shapes sound a little different, but messing with the spring preload makes more of a difference.
I spent way too long trying to get a side screw mount to clear the shift lever arm. It is super challenging to mess with two angled vectors pointed across a Cartesian coordinate system and then adding two rotational components of a round object while locating a screw head and square nut around a central shaft... and thinking about print orientation. I broke my rigid sketch based linear workflow to make that one happen. I had to model separate bodies, then use assemblies to layer the coordinate systems.
Then I decided to stop screwing around and simping for big hardware. Obviously the curved shape of the removable index is a printed spring. I guess I was passively thinking I needed to avoid that flexibility or loading. It took me rotating the side bolt from center-ish, to as high as possible before I saw a good way to limit deflection while keeping a snap fit. The fit is actually too good now. I need to make an easier way to remove the thing and alter a bit of geometry to make more removal clearance.
One of the problems with removal of the index from the body is that the pawls need to be in the highest gears to access the location where there is space to slide it out. This makes the screw retained version want to fly apart once the screw is removed. Then omg it is a pain in the ass to get the thing back together with the index back under the pawls. So to solve this, I made an extra index address at the very end where the pawls can park outside of the removable section. This works fantastic, but creates a new problem. That location will be blocked by the RD high side limit screw on the bike. I have a few ideas of how to remedy the issue, but I think the best one is to make a little barrel limit device that sits on the exposed section of the RD shift cable at the RD, between the clamp bolt and housing termination. That could be removed to give access without altering the RD/cable. Another way, but much more involved design, is to create a release mechanism into the barrel.
I've been wondering if I could somehow add a small amount of adjustment to the whole index by changing the distance between the barrel and central axle by a millimeter or so. I had been thinking of simple ways to create such a variance, but adding a bunch more complexity, it might be possible to add the ~3mm of extra shift cable travel needed to get the pawls past the RD limits without releasing the RD cable.
For the rear cassette, I have plenty of room between an 11 speed 11-28 that I typically ride and my spokes. I wish I could find HG 10t cogs or a 9t built into a lock ring. Alas it is easier to extend the big cog side. While I cannot make a regular cassette cog fit, I can easily create a dished carrier for mounting a small chainring at the spoke side. Pretty silly to me as I never even use the 28t, but it would be funny to joke about the marketing of ""12 speeds"" and how my chainring on the back is smaller than many mountain cassettes now. I have a bunch of 38-42t inner chainrings I could use.
On another tangent... all of the 3d printed brake hoods I have seen are hideous. Still, I wonder about TPE as a replacement for bar tape and maybe even hoods. What if it was more modular. What if it was made so that the print creates ribbon like strands and these are braided on the bars. What if nice bar tape equivalent could be removed without damage. What if it was washable. What if the whole road bike system is made to be serviceable piece meal instead of all or nothing.
Then it occurred to me today, with my index measurement tool I made, all anyone needs to do is measure and print their own tuned spacers between the cogs of the rear cassette and every combination is possible. That is the Occam's Razor of solutions. All the fuss and marketing boils down to the size of those little rings of plastic between the cogs.
